An expandable winding mandrel for internally seizing a substantially cylindrical thin walled yarn holder of a spinning or twisting machine can have gripping segments or members distributed approximately uniformly around its circumference, i.e. in angularly equispaced relationship about an axis.
Receiving bobbins of winding holders with large inner diameters are mounted in certain spinning machines, e.g. glass fiber twisting machines, for processing synthetic fibers.
These winding holders have an inner diameter of, for example, 250 mm and are made of comparatively thin pasteboard.
It is a disadvantage that these winding supports are, for the most part, not exactly cylindrical and moreover do not have a shape which has sufficient stability. When they rotate moreover in the operating state their mounting on the winding mandrel is not reliable, being afflicted with position error and being otherwise problematical.
The gripping mechanism of the winding mandrels should be operable easily. They should be easily operable individually manually. It should also be possible to install a centrally operable mechanism on all the expandable winding mandrels of a spinning or twisting machine. These devices shold not be positively operated under pressure of a pressurizing medium since the clamping force might fail during a pressure drop. The gripping mechanism should have a centering effect to avoid undesirable imbalance as a result of noncentral or nonaxial holding of the winding holder.